Process for the manufacture of alpha, alpha-branched carboxylic acid vinyl esters

ABSTRACT

The invention relates to a process for the manufacture of α,α-branched carboxylic acids vinyl esters comprising the following steps:
         isomerising and converting an olefin feed with CO and water under Koch reaction conditions to make an acid with a ratio of Non Blocking isomers (NB) versus Blocking isomers (B) of NB/B above 1.5, wherein a blocking isomer has always a tertiary carbon atom in alpha position of the carboxylic acid and in the beta position of the carboxylic acid, whereas a non-blocking isomer has primary carbon atoms in the beta position of the carboxylic acid   converting the resulting acid into a vinyl ester.

RELATED APPLICATION DATA

This application is a continuation application of co-pending U.S. patentapplication Ser. No. 14/007,699, filed Oct. 10, 2013, application claimsthe benefit of PCT Application PCT/EP2012/001478 with InternationalFiling Date of Apr. 3, 2012, published as WO 2012/136353 A1, whichfurther claims priority to European Patent Application No. 11002898.2filed Apr. 7, 2011, the entire contents of all are hereby incorporatedby reference.

FIELD OF THE INVENTION

The invention relates to a process for the manufacture of α,α-branchedcarboxylic acid vinyl esters. More in particular the invention relatesto a process for the manufacture of α,α-branched carboxylic acid vinylesters from olefins by means of a Koch synthesis using carbon monoxideas reagent and an acid catalyst and a subsequent vinylation of theα,α-branched acid.

BACKGROUND OF THE INVENTION

Processes for the preparation of α,α-branched carboxylic acids frombranched olefins by means of a Koch synthesis, using carbon monoxide andwater, are known. Thus, Koch, Gilfert and Huiskens developed in 1955 atwo-stage operation (medium pressure synthesis where, in the first stageolefins react with an acid catalyst and carbon monoxide in the absenceof water, followed by a second stage wherein the complex formed by theolefin, carbon monoxide and the acid catalyst is hydrolyzed. Thereaction occurs at temperatures between 50 to 200° C. and pressures upto 100 bar. Generally H₂S0₄, H₃PO₄, HF or Lewis acids such as BF₃ areemployed as catalyst. A review of Koch reactions, which review isincluded herein by reference, may be found in “New Synthesis with CarbonMonoxide”, edited by J.Falbe, ISBN 3-540-09674-4, © by Springer-VerlagBerlin Heidelberg 1980. Such technology is also described in U.S. Pat.No. 3,068,256 to Roming, included herein by reference, and in otherpatent literature.

From EP 1 033 360 a process is known for the synthesis of vinyl estersfrom butene oligomers, wherein butenes are oligomerized, the buteneoligomers are separated from the oligomerized mixture, the buteneoligomers are converted to carboxylic acids which are longer by onecarbon atom, and the resulting carboxylic acids are converted to thecorresponding vinyl esters. The butene oligomers are in particulardibutene, tributene and tetrabutene.

The vinyl esters are well known in the industry as monomer copolymerizedwith other unsaturated functional olefins that are used in coatings,adhesives and composite applications.

The carboxylic acids obtained by way of the Koch synthesis may beconverted to the corresponding vinyl esters. This can be achieved, forexample, by reacting the carboxylic acids with acetylene at normalpressure and 200 to 250° C., preferably in the presence of the zinc saltof the acid to be vinylated (for example, according to Encyl. Polym.Sci. Eng. 17, pp. 426-434, incorporated herein by reference). They mayalso be produced from the corresponding acid by reaction with ethyleneand a copper catalyst.

Alternatively, the vinyl esters can be obtained by transesterificationof the carboxylic acids with further vinyl esters such as vinyl acetateor vinyl propionate (as described, for example, in: Ullman, 4th Edition,Volume 19, pp. 368 ff., incorporated herein by reference. Industry maystart from different sources of olefin oligomers to make the acid.Surprisingly, the inventors have found that the isomer distribution ofan olefin oligomer mixture, and more specially the mixture based on apropylene trimer (so called PT3), has an important influence on thethroughput of the synthesis of the vinyl ester. This relationship wasnot disclosed so far. On the other hand, it is obvious that a higherthroughput is leading to economical and environmental benefits.

Surprisingly, the inventors have found a way to produce acid compositionat a higher throughput in the vinylation step, as compared with theinitial isomer composition.

SUMMARY OF THE INVENTION

Accordingly, the current invention relates to a process for themanufacture of an α,α-branched carboxylic acid vinyl ester as claimed inclaim 1. The invention is of particular relevance when using a propyleneoligomer as olefin feed, in particular a PT3 mixture with a highconcentration of highly branched isomers. Moreover, the invention is ofparticular relevance when the branched carboxylic acid produced by theadapted Koch reaction is subsequently converted into a vinyl ester byreaction with acetylene.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described in more detail hereinafter. The invention isdescribed with respect to propylene oligomers. However, it is to beunderstood that the improved process may be used with other olefinmixtures with a high content of highly branched isomers as well. Thus,the inventors have found new Koch reaction conditions that allowconversion of commercially available propylene oligomers at improvedthroughput into a vinyl ester of an α,α-branched carboxylic acid.

The vinyl esters produced accordingly show attractive properties incoating, adhesive or composite applications. They have copolymer Tg(V10/VA: 25/75) of 26.5° C. or lower, wherein V10 represents thevinylester of a C10 acid, and VA represents vinyl acetate.

A propylene oligomer composition is rather complex and variable. Forexample, the composition of a PT3 may contain olefins with 6, 7, 8, 9,12 and more carbon atoms. The commercially available PT3 gradesgenerally contain from 90 to 98 weight % of C9. However the isomericcomposition within the C9 differs greatly, which has been found toinfluence the vinylation step.

The current process of the invention comprises the determination of theisomeric composition of the olefin mixture, using KOCH reactionconditions that are adapted to the isomeric composition.

Determination of the isomer composition of e.g. a PT3 stream may be donein various ways. One is by hydrogenating the olefin mixture andidentification by gas chromatography. The isomers so identified may begrouped in isomers with one branching alkyl group (such as methyloctane) (BR1), with two branching alkyl groups (such as dimethylheptane) (BR2) and with three (or more) branching alkyl groups (such astrimethyl hexane) (BR3). Table 1 reports the different isomersidentified in PT3 feeds. Identification of the hydrogenated PT3 streamwas done to simplify the isomer composition of the alkene content ofPT3. In theory 219 C9 alkene isomers are possible and afterhydrogenation only 38 C9 alkane isomers are derived there from. So forexample the 2,3-dimethylheptane can be produced from 10 different“nonene” isomers by hydrogenation, see Table 1 for the completeoverview.

TABLE 1 Nonane isomers in a hydrogenated PT3 stream and identificationby gas chromatography Number of Code Name alkene (1) Level branching 901n-nonane 7 0 902 2-methyloctane 11 1 903 3-methyloctane 13 1 9044-methyloctane 13 1 905 2,2-dimethylheptane 7 2 906 2,3-dimethylheptane10 2 907 2,4-dimethylheptane 10 2 908 2,5-dimethylheptane 10 2 9092,6-dimethylheptane 4 2 910 3,3-dimethylheptane 6 2 911*3,4-dimethylheptane 16 2 911* 3,4-dimethylheptane 2 912*3,5-dimethylheptane 7 2 912* 3,5-dimethylheptane 2 9134,4-dimethylheptane 3 1 914 3-ethylheptane 8 1 915 3-ethylheptane 7 1916 2,2,3-trimethylhexane 6 3 917 2,2,4-trimethylhexane 6 3 9182,2,5-trimethylhexane 4 3 919 2,3,3-trimethylhexane 4 3 920*2,3,4-trimethylhexane 9 3 920* 2,3,4-trimethylhexane 3 9212,3,5-trimethylhexane 7 3 922 2,4,4-trimethylhexane 3 3 9233,3,4-trimethylhexane 5 3 924 3-ethyl-2-methylhexane 10 2 9253-ethyl-3-methylhexane 4 2 926 3-ethyl-4-methylhexane 8 2 9274-ethyl-2-methylhexane 6 2 928 2-ethyl-2,2-dimethylpentane 3 3 9292-ethyl-2,3-dimethylpentane 2 3 930 2-ethyl-2,4-dimethylpentane 4 3*stereoisomers (1): number of alkene with this backbone structure

From the complete study for the reaction cascade from the olefinoligomer up to the vinyl ester derived from; the inventors have foundthat ratio of (BR1+BR2)/BR3=Y will determine the throughput ofvinylation reaction. When an olefin mixture is used for the Kochreaction wherein Y is above 20 (Ya) the subsequent vinylation reactionis faster than when an olefin mixture is used wherein Y is below 20(Yb).

It is hypothesized that a Ya type PT3 after the Koch reaction using mildreaction conditions (80° C., 80 bar of CO and about 18% weight water inthe acid catalyst) leads to a composition of branched carboxylic acidsderived from the branching level of the Ya-PT3 composition withoutsignificant isomerisation during the reaction and lead to an acidisomeric composition with a higher proportion of “non blocking” isomers(NB), as defined below, over the amount of “blocking” isomers (B).

Blocking Isomers

Whereas the carbon atom in alpha position of the carboxylic acid isalways a tertiary carbon atom, the carbon atom(s) in β position caneither be primary, secondary or tertiary. Neodecanoic acids (V10) with asecondary or a tertiary carbon atoms in the β position are defined asblocking isomers (Schemes a & b).

Blocking isomers not only comprise alkyl groups on the (alpha) carbonnext to the acid group, which is therefore a tertiary carbon atom, butalso one or more alkyl groups attached to the next (beta) atom.Non-blocking isomers on the other hand have beta atoms that are primary(i.e., without branching).

Preferably, vinylation is carried out on a mixture of carboxylic acidscontaining both non blocking isomers and blocking isomers in a ratioNB/B that is greater than 1.5.

Interestingly, by selecting more severe reaction conditions for theproduction of the branched carboxylic acids (by Koch reaction) startingfrom a type Yb PT3 feed the inventors have found that they could produceYa-type C10 branched carboxylic acids.

Isomerisation may be performed in the Koch reaction by various means.For instance, the isomerisation seems to take place under the Kochconditions when the level of water in the catalyst is below 12 wt % fora residence time of at least 30 minutes.

By including an isomerisation step in the Koch reaction, resulting in aNB/B ratio of at least 1.5, it was therefore found that the throughputof the reaction improved from a 4.2-4.5 ton/hour for a type Yb PT3 feedto 5.3-5.6 ton/hour.

This improvement was found, starting from the branched carboxylic acidsproduced according to the modified Koch reaction and reacting the samewith acetylene and Zn catalyst.

1. A composition of α,α-branched carboxylic acid vinyl esters frompropylene oligomers comprising: a vinyl ester mixture of neo-acidsderived from propylene oligomer olefin feed having an isomer ratio of(BR1+BR2)/BR3=Ya above 20, with BR1=weight of propylene oligomer olefinwith one branching alkyl group, BR2=weight of propylene oligomer olefinwith two branching alkyl groups and BR3=weight of propylene oligomerolefin with three or more branching alkyl groups, wherein the neo-acidshave a ratio of Non Blocking isomers (NB) versus Blocking isomers (B) ofNB/B above 1.5, where a carbon atom is always quaternary, the carbonatom(s) in β position can either be secondary, tertiary, or quaternary,acids with a tertiary or a quaternary carbon atoms in the β position aredefined as blocking isomers.
 2. The composition of claim 1 wherein thepropylene oligomer olefin feed is mainly a trimer of propylene or mainlya tetramer of propylene.
 3. The composition of claim 7 wherein thepropylene oligomer is mainly a trimer of propylene with Ya compositionand wherein the resulting acids are reacted with acetylene in presenceof a zinc salt to produce vinyl esters of branched carboxylic acids witha copolymer Tg of 26.5° C. or lower.
 4. The composition of claim 1wherein the resulting acid is reacted with acetylene in presence of azinc catalyst.
 5. The composition of any one of claim 1, wherein theresulting acid is reacted with acetylene in presence of a zinc catalystwith a throughput of the reaction of at least 5.3 ton/hour.
 6. Acopolymer comprising the vinyl esters produced according to claim
 1. 7.The copolymer of claim 6, wherein the copolymer comprises vinyl ester ofa C10 acid and vinyl acetate.
 8. The copolymer of claim 7, wherein thecopolymer comprises a 25/75 ratio of vinyl ester of a C10 acid to vinylacetate, and has a glass transition temperature of 26.5° C. or lower. 9.A polymer composition for coating, adhesive or composite applications,comprising the copolymer of claim 6.